Upcycled battery waste gives cells about twice the life, in lab tests

A battery that has reached the end of its life is, for the most part, a problem to be shipped away. Researchers at Worcester Polytechnic Institute want it to become a source of parts for a new battery. In a study published in Advanced Energy Materials, a team led by professor Yan Wang converted mixed battery waste into upcycled materials for both the cathode and the anode, and built pouch cells (flat, sealed batteries) from them that outlasted cells made with commercial materials.

The pressure behind the work is easy to state. As lithium-ion battery use grows, so does the demand for critical materials and the volume of discarded batteries. Many current recycling methods focus on recovering the cathode, and mixed battery waste is difficult to process into products of high value. The team therefore set out to upgrade both the cathode and the graphite recovered from that waste, rather than stopping at raw materials.

The process works in two steps. Mixed, low-nickel cathode material is converted into a high-performance cathode called NMC622, and recovered graphite is purified and modified to become battery-grade anode material. Tests found improved lithium-ion transport and cycling stability in the cathode, and better interfacial kinetics and durability in the graphite anode. When the team assembled full pouch cells using only these upcycled parts, the cells showed fewer side reactions and approximately twice the cycle life of cells built with commercial materials, retaining 70% of their capacity after 2,590 cycles.

The team also estimated what the route could mean outside the laboratory. According to their analyses, it could use more than 95% of waste materials, increase profitability by 22.9%, and reduce greenhouse gas emissions by 27% and energy consumption by 29.4% compared with the reference recycling route. These are estimates from the researchers' own analyses, not measurements from an operating plant, and the study does not give costs or a timetable for industrial use.

For recyclers, the gain would be turning waste that is hard to sell into components that battery makers can use directly. For battery manufacturers, it points to a more circular supply, with fewer resources and less energy needed to produce new materials. The authors describe a path beyond recovering raw materials toward making high-performance batteries from complex waste. Whether that path reaches factories, and how quickly, depends on tests beyond the laboratory that the study does not yet report.